<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CSS选择器</title>
    <link rel="stylesheet" href="css_three.css">
</head>
<body>
    <h1>CSS选择器</h1>
    <h2>通用选择器</h2>
    <div id="main">ID选择器</div>
    <p class="news_title">类选择器</p>
    <h3>元素选择器</h3>
</body>
</html>